This invention relates to lights, especially for a motor vehicle, in particular where the purpose of the light is to provide illumination, but also including lights having as their only or primary purpose the giving of an indication or signal. These various kinds of lights will be referred to generically in this Application, for convenience, as headlights.
European published patent specification No. 0 847 894 discloses an illuminating or signalling device for a vehicle which comprises a casing, a fixed lamp and a reflector mounted for movement in the casing and being directly connected to the casing. In some applications, particularly in a foglight, the temperature in the upper part of the reflector can reach more than 200xc2x0 C. Such a temperature can cause deformation and softening of some of the components of the headlight, particularly if they are of plastics material. The connection between the reflector and casing is particularly critical in this regard, and this effect is increased the more the movement of the reflector with respect to the lamp has to be accurate enough to give a correct beam under all circumstances.
One object of the present invention is to provide a headlight (i.e. an illuminating or signalling device, as defined above) which has increased resistance to heat, especially in the region of the connection between the reflector and the casing.
According to the invention, an illuminating or signalling device for a vehicle comprises a casing and a reflector and is characterised in that it includes a cradle connecting the reflector to the casing and having an aperture in its upper part.
This aperture corresponds to the zone of the cradle which would otherwise be the portion of the latter which is most exposed to heat. In addition, the aperture enables the cradle to undergo some thermal expansion. In this way the thermal resistance of the cradle is improved, which enables the reflector to be well positioned with respect to the lamp. In addition, the aperture which is provided in accordance with the invention reduces the volume of the cradle and gives it a size which enables certain steps in the fitting of the cradle with respect to the reflector to be carried out, for example assembly by pivoting movement, which would otherwise not have been possible.
Moreover, the aperture prescribed by the invention provides an indexing feature for correct mounting of the cradle in the headlight. Finally, it enables the amount of material used to be reduced. This in turn gives a reduction in both weight and cost, considerations which are becoming more important in view of the now current use, for this type of component of plastics materials, of sophisticated compositions which have high heat resistance but which are often difficult to work.
According to a preferred feature of the invention, the said aperture includes a slot.
The cradle may be secured rigidly to the reflector. Alternatively or in addition, the reflector may be mounted so that it is capable of some movement with respect to the casing, such as rotational movement.
According to another preferred feature of the invention, the headlight includes an adjusting screw rotatable on the casing and meshing with a threaded element of the cradle.
The headlight does of course include a light source, referred to herein as a lamp. The lamp may be mounted rigidly on the casing.
The headlight may have a rear wall of plastics material, with a lamp holder fixed to this rear wall and a metal plate fixed to the rear wall. This metal plate reinforces and stiffens the rear wall. The mechanical strength of the rear wall, even under the effect of heat, is thereby increased. Moreover, the metal plate receives some of the heat from the rear wall, and may also even be heated directly by the lamp, to dissipate this heat into the air around the metal plate (which thereby constitutes a radiator). This maintains the rear wall at a relatively low temperature. Deformation of the rear wall is therefore very much reduced, and the positioning of the lamp with respect to the reflector, in order to give a correct beam, is thereby preserved.
The headlight preferably includes a cover glass, and an intermediate member which connects the cover glass to the casing, with a screen extending forward from an upper zone of the casing towards the cover glass. With this arrangement, the screen receives the rising hot air. Some of the heat is then captured by the screen and no longer by the intermediate piece. In this way the risk of deformation of the intermediate piece is reduced. As to the screen, it can be deformed by quite a large amount without adversely affecting operation of the headlight.
In preferred embodiments the headlight is an illuminating device, which may in particular be a foglight.
Further features and advantages of the invention will appear more clearly on a reading of the following detailed description of preferred embodiments of the invention, which is given by way of non-limiting example only and with reference to the accompanying drawings.